[PATCH] powerpc: Fix PowerPC 750CL CPU features
jwboyer at linux.vnet.ibm.com
Fri Apr 13 03:10:56 EST 2007
On Thu, 2007-04-12 at 18:41 +0200, Segher Boessenkool wrote:
> > PowerPC 750CL has high BATs. The patch below sets cpu_features to
> > match that.
> > Without it, the original firmware mappings in the high BATs aren't
> > cleared
> > which can cause "odd" address translations to occur.
> > - .cpu_features = CPU_FTRS_750,
> > + .cpu_features = CPU_FTRS_750GX,
> The difference between these two is
> #define CPU_FTRS_750GX (CPU_FTR_DUAL_PLL_750FX | CPU_FTR_HAS_HIGH_BATS)
> #define CPU_FTRS_750 (CPU_FTR_COMMON)
> 750GX excludes COMMON, which seems like a bug. With
CPU_FTR_COMMON is actually a nop in this case anyway. It should
probably be listed for "completeness", but it's defined to be 0 so it
doesn't really do anything.
> your change, 750CL uses DUAL_PLL_750FX; does it actually
> have that feature?
No, it doesn't, I missed that in the GX feature list. Good catch.
> Either way, it seems a good idea to create a CPU_FTRS_750CL,
> the CL is an evolution of the CX, not the FX/GX (in name
> at least, dunno about the gory details).
I can do that, or I can just do:
CPU_FTRS_750 | CPU_FTR_HAS_HIGH_BATS
> > - .cpu_setup = __setup_cpu_750cx,
> > + .cpu_setup = __setup_cpu_750fx,
> Same thing here. Are you sure 750CL doesn't need
> the NAP workaround? [Is anyone sure the 750CX
> actually needs it -- the comment in cpu_setup_6xx.S
> doesn't instill much confidence.]
This should be fine.
I'll send out a newer version, and fixup the description with the
comment Milton made.
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